RE: [PATCH v2] Support Intel AVX10.1

["Jiang, Haochen" <haochen.jiang@intel.com>]

> > I have an open after digging into .arch directives corner cases when we choose
> > to set/clear bits for AVX512 in AVX10.1.
> >
> > Should directives like .noavx512f .avx10.1 open zmm registers?
> 
> You mean the combination of the two, in that order? Yes, of course.
> 
> > For directive
> > .noavx512fp16 .avx10.1, should we enable zmm registers for AVX512FP16 insts?
> 
> And then yes here, too.
> 
> In both cases what remains to be determined is how vector size is to
> be limited. I think that wants to be independent of the .avx10.<N>.
> 

That also met my expectation. And it will make everything easy to
understand.

> >> Right, a boolean is fine initially, but with the spec explicitly allowing the 128-
> >> bits-only mode, I'm pretty sure we ought to support that rather sooner than
> >> later. After all, more artificial environments (emulators,
> >> virtualization) may expose feature combinations not ever seen on real
> >> hardware.
> >
> > After I think twice on that, I suppose maybe it is not that appropriate to put it
> > into i386_opcode_modifier since in AVX10, the vector width is depends on CPU.
> > I suppose i386_opcode_modifier is a feature for instructions but not CPU.
> 
> I disagree. See the uses of EVex, for example. As said above, I think
> maximum vector width and ISA extensions want dealing with separately,
> and only the latter would generally qualify for Cpu* flags. Furthermore
> recall that the attribute wants widening sooner or later, and Cpu*
> flags are uniformly boolean. Only attributes may have numeric values.

After I checked code, I still miss the point here.

My concern is how to actually disable the zmm registers for AVX10/256
and ymm registers for theoretical AVX10/128. I suppose i386_opcode_modifier
is more related to building up the whole encoding. But each AVX10.X/256 is an
actual arch.

Adding a feature in i386_opcode_modifier can indicate what is the maximum
vector length the instruction is allowed on all archs but has nothing to do with
disabling zmm registers on an 256-bit only arch.

I might be wrong on the understanding on what to add in i386_opcode_modifier.
Please just correct if there is something wrong.

Thx,
Haochen

> 
> Jan